Gas-purification apparatus



July 13, 192 1,592,649

F. W. SPERR, JR GAS PURIFICATION APPARATUS Original Filed Dec. 8, 1921.5? samzw CJEBUNJTE 50L 0770K.

APPARATUS F01? CDMFLETE FUEIFJCATJ'UN UFEM'S Patented July 13, 1926.

FREDERICK W. SPEZRR, JR., PITTSBURGH, PENNSYLVANIA,

ASSIGNOR TO THE KOP- PERS COMPANY, OF PITTSBURGH, PENNSYLVANIA, ACORPORATION OF PENNSYL- VANIA.

GAS-PURIFICATION APPARATUS.

Original application filed December 8, 1921, Serial No. 520,808. Dividedand this application filed May 23, 1924, Serial No. 715,401. RenewedMarch 3, 1826.

This invention relates to the removal of hydrogen sulphide and othernoxious constitutents, such as hydrocyanic acid, from gases containingthem. An object of the to subject the purified gas to any iron oxidetreatment. The invention is of particular utility in connection with agas purification process operating generally in accordance with thatprocess, described and claimed in Letters Patent of the United States ofDavid L. Jacobson, dated September 6, 1921, No. 1,390,037. Broadlystated, such gas purification process consists in bringing the gas to bepurified into direct contact with an o alkaline absorbent agent, such asa solution of sodium carbonate, to absorb the noxious constituents fromthe gas, and then subjecting the absorbent agent containing the absorbed'mpurities to aeration to remove the absor ed impurities and toregenerate the absoiiilent agent so as to render it available for entinvention, however, is not confined to the process of the Jacobsonpatent but may be applied to a variety of processes characterized by thefeature of substantially continuous regeneration of the gas purifyingmedium.

A process such as that of Jacobson requires two essential parts ofapparatus, i. e., the

chamber in which the gas is-brought into contact with the purifyingliquid, and the chamber in which the liquid containing the.

absorbed impurities is regenerated. In prac- 49 tice the first chamberis designated thefabsorber and the second the actifier. These two termswill be employed in the following description.

The removal of the last traces of the hydrogen sulphide from the gas isa require ment that most gas companies must meet, being imposed by lawin most places. According to this invention, the last traces of hydrogensulphide are removed from the 50 gas by a system of liquid purification,complete in itself, without any resort whatever to ordinary iron oxidepurification of the rther gas purification. The presgas discharged fromthe liquid purificatiion plant.

In addition to the general object recited above, the invention has forfurther objects such other improvements or advantages in operation andresults as are found to obtain in the apparatus hereinafter described orclaimed.

In the accompanying drawing forming a part of thisspecifica-tion andshowing, for purposes of exemplification, a preferred form and manner inwhich the invention may be embodied, but without limiting the claimedinvention specifically to said illustrative instance:

The figure illustrates .the apparatus for carrying out the invention.

In accordance with the invention, the gas is discharged from an absorberthat is op erated with a normal rate of circulation ofi purifying liquidand gas therethrough, and such gas is passed through a second absorber,supplied with a circulation of fresh gas purifying solution. Thesolution from the second absorber is circulated through a second andseparate actifier, for regeneration of the purifying liquid. In thesecond absorber, the last traces of hydrogen sulphide are readilyremoved from the gas. invention, a relatively fresh solution is readilymaintained in the second absorber and actifier, and this-solution isVery active in removing the small amounts of hydrogen sulphide, in thesecond stage of the urificationprocess. A preferred mode 0 operationconsists'in employing a relatively strong solution in the first absorberand actifier, which constitutes the first stage of the proc ess, and arelatively weaker solution in the second absorber and actifier, whichconstitutes the second stage of the process. For example, a solutioncontaining five or six ercent sodium carbonate may be employe in thefirst absorption and regeneration stage and one containing two percentsodium carbonate in the second absorption and regeneration' stage. Inthis Way, any s ray mechanically'carried over from the rst absorber wille caught in the second, While any spray passing out of the secondwill beso dilute that the mechanical loss of material is inconsiderable. Theweak solution, moreover,

By the v is readily actified and maintained in a fresh conditionessential for the removal of small amounts of hydrogen sulphide; whilethe strong solution has the advantage of a high capacity for the removalof hydrogen sulphide when relatively large amounts are present.

Referring to the accompanying drawing: the gas containing hydrogensulphide is first passed into the absorber A. The purifying solution ispumped into the top of the absorber by the pump 6 from the sump B andabsorbs the bulk of the hydrogen sulphide from the gas (and hydrocyanicacid it any be present) together with some carbon dioxide. The gasenters the bottom of the absorber A through the gas line e anddischarges from the top through the gas line k. The foul solutiondischarges from the bottom of the absorber A through the solutiondischarge line a and runs into the sump C. From this sump C the foulsolution is pumped by the pump a through the solution line 0 into thetop of the actifier D. Air is blown upwardly through the actifier D bythe fan E; the air effects a regeneration of the solution dischargedinto the top of the actifier D and carries out the absorbed impuritiesthrough the discharge pipe F. The regenerated solution runs from thebottom of the actifier D through the solution line cl back into the sumpB from which it is continuously circulated through the solution line I)back to the absorber A.

The gas from the absorber A, containing relatively small amounts ofhydrogen sulphide (for example, from ten to sixty grains per 100 cubicfeet) passes through the gas line M into the second absorber G. toundergo the second stage of the purification treatmentf A relativelydilute purifying solu-' tion is pumped into the top of the absorber Gthrough the solution line it from sump H and in said absorber G the saidsolution ahsorbs from the gas the last traces of hydrogen sulphide (andhydrocyanic acid, if any be present) together with some additionalcarbon dioxide. The solution then flows from the bottom of the secondabsorber through the solution line i into the sump I and is pumpedtherefrom by the pump 1' throughthe solution line i into the top of theactifier J. Air is blown upwardly through this actifier from the fan Kand effects a very rapid regeneration of the fouled solution in theactitfier J. The air and impurities pass out through the'pipe L. Theregenerated solution from the bottom of actifier J runs through thesolution line h into sump H and from said sump H is continuously pumpedback by pump h through solution line hover theabsorber G. Thearrangement contemplated in this invention is not necessarily limited totwo sets of absorbers and actifiers, but it may, in certain cases, beadvantageous to use a plurality of sets, the essential requirement beingthat each absorber is connected with a separate actifier. Moreover, eachset may consist of two or more absorbers connected with two or moreabsorbers connected with two or more actifiers (this being desirablewhen large volumes of gas are to be handled).

Economy may be obtained by passing the air from the actifier J into theactifier D, especially when the gasentering the second stage absorber Gis very low in H S. Even with the separate blowers shown, the amount ofair required is much less than that required in purifying the gascompletely in a single absorber. The apparatus required is smaller andless liquid circulation is needed.

The arrangement of apparatus shown has the advantage that the absorbersmay be operated in parallel whenever it is unnecessary to remove thelast traces of hydrogen sulphide. In this event, much larger volume ofgas can be treated by operation in parallel. For this purpose, the twoabsorbers may be made the same size and the two actifiers also of thesame size. In operating the apparatus in series for the complete removalof hy-- drogen sulphide as described above, valves a, a and a are openedwhile valves a and a are closed. The gas enters the absorber A throughthe inlet pipe P and passes into the absorber G through the pipe m. Thepurified gas finally emerges through the pipe R. When it is desired tooperate in parallel, valve (1' is closed while valves 0, a, a and a areopened. The gas enters through the inlet pipe P and divides. passinginto both absorbers and emerging from the top of each through the pipeR. In parallel operation, the strength of the solution is preferablykept the same in all parts of the system.

The arrangement of the apparatus shown has the further advantage thateither of the absorbers may be operated as an independent unit in casethe other is shut down. In operating absorber A alone, valves (1 and aare open and valves a, a and a are closed. In operating absorber Galone, valves a and a are open, while valves (1, a and a are closed.

The invention, as hereinbefore set forth, may be variously embodiedwithin the scope of the claims hereinafter made.

This application is a division of my prior application for LettersPatent of the United States for gas purification process and apparatusfiled December 8, 1921, Serial No. 520,808.

I claim:

1. Apparatus for effecting purification of gases, comprising, aplurality of individual absorbers. actifiers for the respectiveabsorbers. means formaintaining a continuous circulation of liquid backand forth between each absorber and its corresponding actifier,

iza

and gas circulation means embodyil? contion of liquid back and forthbetween each 10 trolling devices for alternatively e ecting absorber andits corresponding actifier, and circulation of a gas through theabsorbers gas circulation means embodying controlling in series or inparallel, substantially as specievices for alternatively efi'ectingclrculation fied. I of a gas through the absorbers in series or 2.Apparatus for effecting purification of in arallel, substantiall asspecified. 15

individual abn testimony whereo I have hereunto set gases, comprising agair o sorbers, actifiers or t e respective absorbers, my hand. meansfor maintaining a continuous circula- FREDERICK W. SPERR, JR.

